Methodology for development of the Allergic Rhinitis and its Impact on Asthma guideline 2008 update

BACKGROUND

We describe the methodology for the 2008 update of the Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines. The methodology differs from the 2001 edition in several respects. The most prominent change is the application of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to compiling evidence, assessing the quality of evidence and grading of recommendations.

METHODS AND RESULTS

Representatives of the GRADE working group joined the ARIA guideline panel to achieve these tasks. While most recommendations result from existing systematic reviews, systematic reviews were not always available and the panel compiled the best available evidence in evidence profiles without conducting actual reviews. The panel conducted two meetings and used the GRADE criteria to assess the quality of evidence (four categories of high, moderate, low and very low) and the strength of recommendation (strong and weak) based on weighing up the desirable and undesirable effects of management strategies, considering values and preferences influencing recommendations, and resource implications. The guideline panel has chosen the words 'we recommend'--for strong recommendations and 'we suggest'--for weak recommendations. Both categories indicate the best course of action for a given patient population, but their implementation, requires different considerations as we describe subsequently in this article.

CONCLUSIONS

The 2008 update of the ARIA guidelines has become more evidence-based. Future iterations of the guidelines will further be improved by following the described processes even closer, such as ensuring availability of updated high quality systematic reviews for each question.

Nerve growth factor involvement in liver cirrhosis and hepatocellular carcinoma

AIM: To define NGF (nerve growth factor) and its high-affinity receptor trkA^NGF presence and distribution in fibrotic liver and in HCC, and to verify if NGF might have a role in fibrosis and HCC.

METHODS: Intracellular distribution of NGF and trkA^NGF were assessed by immunohistochemistry and immuno-electron microscopy in liver specimens from HCC, cirrhosis or both. ELISA was used to measure circulating NGF levels.

RESULTS: NGF and trkA^NGF were highly expressed in HCC tissue, mainly localized in hepatocytes, endothelial and some Kupffer cells. In the cirrhotic part of the liver they were also markedly expressed in bile ducts epithelial and spindle-shaped cells. Surprisingly, in cirrhotic tissue from patients without HCC, both NGF and trkA^NGF were negative. NGF serum levels in cirrhotic and/or HCC patient were up to 25-fold higher than in controls.

CONCLUSION: NGF was only detected in liver tissue with HCC present. Intracellular distribution suggests paracrine and autocrine mechanisms of action. Better definition of mechanisms may allow for therapeutic and diagnostic/prognostic use of NGF.

Predictive value of allergy and pulmonary function tests for the diagnosis of asthma in elite athletes

BACKGROUND

Asthma is frequently found in athletes, often associated with rhinitis and allergy.

AIM

To study the predictive value of allergy and pulmonary function tests for the diagnosis of asthma in athletes.

SUBJECTS AND METHODS

Ninety-eight national preOlympic athletes underwent an accurate medical examination including a validated questionnaire for asthma and rhinitis, spirometric recordings and skin prick testing with a panel of the most frequent inhalant allergens. Bronchodilator and/or exercise challenge were also performed in asthmatic subjects.

RESULTS

Clinical asthma was present in 20.4% of athletes, rhinitis in 35.3% (in 21.4% of cases alone and in 13.9% associated with asthma). Positive prick tests were recorded in 44.4% of athletes (in 60.5% of asthmatics, in 95.2% of rhinitics and in 21.0% of nonasthmatic - nonrhinitic subjects). Mean spirometric values and distribution of abnormal values were not different among asthmatics, rhinitics and nonasthmatics - nonrhinitic patients. Skin-tests positivity was not related to the abnormal spirometric data found in individual cases. Provocation tests with bronchodilators or exercise did not appear sensitive enough to diagnose mild forms of asthma in subjects with normal basal spirometric values.

CONCLUSIONS

Allergy testing and spirometry should be performed routinely in athletes because of the high prevalence of allergy, rhinitis and asthma in this population. However, the predictive value of these tests and of the bronchial provocation tests performed in this study seems too low to document mild or subclinical asthma in athletes.

Thymosin 1 activates the TLR9/MyD88/IRF7-dependent murine cytomegalovirus sensing for induction of anti-viral responses in vivo

Reactivation of latent human cytomegalovirus following allogeneic transplantation is a major cause of morbidity and mortality and predisposes to severe complications. Thymosin alpha1 (Talpha1), a naturally occurring thymic peptide, is approved for treatment of some viral infections and as an immune adjuvant. Talpha1 successfully primed dendritic cells (DCs) for anti-microbial T helper type 1 resistance through Toll-like receptor (TLR) 9 signaling. We sought to determine here whether Talpha1 could play a role in murine cytomegalovirus infection (MCMV). To this purpose, susceptible, resistant and TLR-deficient mice were infected with MCMV, treated with Talpha1 and assessed for protection in term of microbiological and immunological parameters. Talpha1 protected susceptible and resistant mice from MCMV infection. The anti-viral effect of Talpha1 occurred through the activation of plasmacytoid DCs via the TLR9/myeloid differentiation primary response gene 88-dependent viral recognition sensing, leading to the activation of IFN regulatory factor 7 and the promotion of the IFN-alpha/IFN-gamma-dependent effector pathway.

Immunopharmacology of thymosin alpha1 and cytokine synergy

Thymosin alpha1 (Talpha1) is a 28 amino acid biologically active protein cleaved from positions 2-29 of a precursor protein, prothymosin alpha. Since its discovery, Talpha1 has been administered to animals and humans in a wide variety of settings and its pharmacologic effects are to enhance cellular immunity. Talpha1 administration is highly effective in settings where irradiation, chemotherapy, tumor burden, or immune senescence have caused a reduction of T cell number and/or function. Recent in vitro studies, including the one reported here, suggest that Talpha1 may act via pathways commonly used by various cytokines. This raises the possibility that Talpha1 and cytokines may have synergistic activity through potentiation of cytokine activity by Talpha1. Improved control of tumor growth when tumor-bearing mice were treated with Talpha1 and high doses of IL-2 has been previously reported. We extended those studies with the Lewis lung carcinoma mouse model using IRX-2, a natural well-defined biologic containing multiple cytokines, in combination with Talpha1 (IRX-3). Although IRX-2 was effective alone (using doses that contain significantly less IL-2 than in most typical studies), adding Talpha1 led to significant improvement in survival of the tumor-bearing mice. Based on these observations, the immunopharmacology of Talpha1 predicts an important clinical role for Talpha1 in the restoration of cellular immune activity when used in combination with cytokines. Patients who experience immune suppression due to the presence of tumor, irradiation, and/or chemotherapy or aging of the host would most benefit from this treatment combination.

Nonspecific provocation of target organs in allergic diseases: EAACI-GA(2)LEN consensus report

It is widely accepted that nonspecific tissue reactivity is a distinct pathophysiological hallmark of allergic diseases, influenced by genetic and environmental factors different from those involved in causing sensitization and allergen response of target organs. This consensus document aims at reviewing procedures currently used for nonspecific provocation of the bronchi, nose and eye and for measuring their responsiveness to nonspecific stimuli.

Thymosin alpha1: an endogenous regulator of inflammation, immunity, and tolerance

Thymosin alpha1 (Talpha1), first described and characterized by Allan Goldstein in 1972, is used worldwide for the treatment of some immunodeficiencies, malignancies, and infections. Although Talpha1 has shown a variety of effects on cells and pathways of the immune system, its central role in modulating dendritic cell (DC) function has only recently been appreciated. As DCs have the ability to sense infection and tissue stress and to translate collectively this information into an appropriate immune response, an action on DCs would predict a central role for Talpha1 in inducing different forms of immunity and tolerance. Recent results have shown that Talpha1: (a) primed DCs for antifungal Th1 resistance through Toll-like receptor (TLR)/MyD88-dependent signaling and this translated in vivo in protection against aspergillosis; (b) activated plasmacytoid DCs (pDC) via the TLR9/MyD88-dependent viral recognition, thus leading to the activation of interferon regulatory factor 7 and the promotion of the IFN-alpha/IFN-gamma-dependent effector pathway, which resulted in vivo in protection against primary murine cytomegalovirus infection; (c) induced indoleamine 2,3-dioxygenase activity in DCs, thus affecting tolerization toward self as well as microbial non-self-antigens, and this resulted in vivo in transplantation tolerance and protection from inflammatory allergy. Talpha1 is produced in vivo by cleavage of prothymosin alpha in diverse mammalian tissues. Our data qualify Talpha1 as an endogenous regulator of immune homeostasis and suggest that instructive immunotherapy with Talpha1, via DCs and tryptophan catabolism, could be at work to control inflammation, immunity, and tolerance in a variety of clinical settings.

Thymosin Alpha 1: From Bench to Bedside

After the initial dramatic effects, observed in a Lewis lung carcinoma animal model, using a combination of thymosin alpha 1 (Talpha1) and interferon (IFN) after cyclophosphamide, a number of other preclinical models in mice (Friend erythroleukemia and B16 melanoma) and in rats (DHD/K12 colorectal cancer liver metastasis) have confirmed the efficacy of the combination therapy with Talpha1 and either IFN or IL-2 plus chemotherapy. These results provided the scientific foundation for the first clinical trials using Talpha1 in combination with BRMs and/or chemotherapy. Pivotal trials in advanced non-small cell lung cancer (NSCLC) and melanoma with Talpha1 and IFN-alpha low doses after cis-platinum or dacarbazine produced the first evidence of the high potentiality of this approach in the treatment of human cancer. The combination of Talpha1 and IFN-alpha was also used in patients affected by chronic B and C hepatitis including IFN-nonresponders and infected by precore mutants or genotype 1b. Further studies demonstrated additional biological activities clarifying the mechanism of action of Talpha1, partially explaining the synergism with IFN. It has been shown the capacity of activating infected dendritic cells through Toll-like receptor signaling, thus influencing the inflammation balance, and of increasing the expression of tumor, viral, and major histocompatibility complex (MHC) I antigens. Dose-response studies suggested the possibility of improving the efficacy of this molecule reducing the overall toxic. Based on these information two clinical trials are ongoing: a large phase II on advanced melanoma patients treated with Talpha1 at different doses after dacarbazine and a phase III one, on IFN-resistant hepatitis C virus (HCV) patients treated with a triple combination (IFN, ribavirin, and Talpha1).

Rhinitis and asthma in athletes: an ARIA document in collaboration with GA2LEN

This consensus document is aimed at reviewing evidence that the rhinitis-asthma links have peculiar features in athletes. Beside a review of epidemological data on the high prevalence of rhinitis and asthma in athletes, the effects on intense physical exercise on the immune system and repiratory functions are discussed, with special reference to the role of allergens and pollutants. In extending the Allergic Rhinitis and its Impact on Asthma (ARIA) recommendations to athletes, the issue is addressed of adapting diagnosis and management to criteria set by the International Olympic Committee (IOC) and regulations adopted by the World Anti-Doping Agency (WADA).

Thymosin alpha1 activates dendritic cell tryptophan catabolism and establishes a regulatory environment for balance of inflammation and tolerance

Thymosin alpha1 (Talpha1), a naturally occurring thymic peptide, primes dendritic cells (DCs) for antifungal T-helper type 1 resistance through Toll-like receptor 9 (TLR9) signaling. As TLR9 signaling also activates the immuno-suppressive pathway of tryptophan catabolism via indoleamine 2,3-dioxygenase (IDO), we examined Talpha1 for possible induction of DC-dependent regulatory effects. Talpha1 affected T-helper cell priming and tolerance induction by human and murine DCs and induced IDO expression and function in the latter cells. IDO activation by Talpha1 required TLR9 and type I interferon receptor signaling and resulted in interleukin-10 production and generation of regulatory T cells. In transfer experiments, functionally distinct subsets of differentiated DCs were required for priming and tolerance to a fungal pathogen or alloantigens. In contrast, Talpha1-primed DCs fulfilled multiple requirements, including the induction of T-helper type 1 immunity within a regulatory environment. Thus, instructive immunotherapy with Talpha1 targeting IDO-competent DCs could allow for a balanced control of inflammation and tolerance.

Feasibilty of in utero DNA vaccination following naked gene transfer into pig fetal muscle: Transgene expression, immunity and safety

The high toll of death among first-week infants is due to infections occurring at the end of pregnancy, during birth or by breastfeeding. This problem significantly concerns industrialized countries also. To prevent the typical "first-week infections", a vaccine would be protective as early as at the birth. In utero DNA immunization has demonstrated the effectiveness in inducing specific immunity in newborns. We have already published results of a 2-year follow-up showing long-term safety, protective antibody titers at birth and long-term immune memory, following intramuscular in utero anti-HBV DNA immunization in 90-days pig fetuses. We have now analyzed further parameters of short-term safety. Two different reporter genes were injected in the thigh muscles of 90-days fetuses. At 8 days following DNA injection, we found high-level of transgenes expression in all injected fetuses. A step gradient of expression from the area of injection was observed with both reporter genes. CMV promoter/enhancer produced higher levels of expression compared to SV40 promoter/enhancer. Moreover, no evidence of local or systemic flogistic alterations or fetal malformations, mortality or haemorrhage following intramuscular injection were observed. A single anti-HBV s-antigen DNA immunization in 90-days fetuses supported protective antibody levels in all immunized newborns, lasting at least up to 4 months after birth. Our report further sustains safety and efficacy of intramuscular in utero naked gene transfer and immunization. This approach may support therapeutic or prophylactic procedure in many early life-threatening pathologic conditions.

Microfabricated biocapsules provide short-term immunoisolation of insulinoma xenografts

This study examines the viability and functionality of two insulinoma cell lines, RIN (1048) and betaTC6F7, encapsulated within microfabricated biocapsules. Surface and bulk micromachining are integrated in the biocapsule fabrication process, resulting in a diffusion membrane with uniform pore size distribution as well as mechanical and chemical stability, surrounded by an anisotropically-etched silicon wafer, which serves as the encapsulation cavity. Insulinoma cells (4500 cells/biocapsule) were enclosed within these microfabricated biocapsules and subjected to a static incubation study after either implantation in BALB-C mice or incubation in vitro. Examination of retrieved microfabricated biocapsules revealed an insulin stimulatory index of approximately 1.5 for encapsulated RIN cells and 3.6 for encapsulated betaTC6F7 cells for biocapsules with 18 nm pore sized microfabricated membranes, similar to indices of biocapsules incubated in vitro. There was an 80% decrease in cell stimulatory response between in vitro and in vivo 66 nm-biocapsules as compared to 20% for 18 nm-biocapsules, indicating that the immunoisolatory effectiveness depends greatly on achieving uniform pore sizes in the size range of 18 nm or smaller. The present study demonstrates the feasibility of using microfabricated biocapsules for the immunoisolation of insulinoma cells lines. The microfabricated biocapsule may serve as an alternative to conventional polymeric based biocapsules for possible use as in vivo insulin secreting bioreactor.

Differentiation of human melanoma cells induced by cyanidin-3-O-beta-glucopyranoside

Great attention has been recently given to a flavonoid of the anthocyanin class, cyanidin-3-O-beta-glucopyranoside (C-3-G), which is widely spread throughout the plant kingdom, and is present in both fruits and vegetables of human diets. In this study, we investigated the effect of C-3-G on proliferation and differentiation of human melanoma cells. Both morphological and functional parameters were evaluated, using electron and confocal microscopy, cytofluorometric analysis, HPLC assay, Western blot analysis, and enzymatic assay, as appropriate. A treatment with a single dose of C-3-G decreased cell proliferation without affecting cell viability and without inducing apoptosis or necrosis. The mitotic index and cell percentage in S phase were significantly lower in C-3-G treated cells compared with untreated control. C-3-G treatment induced, in a dose- and time-dependent manner, melanoma cell differentiation characterized by a strong increase in dendrite outgrowth accompanied with a remodeling of the microtubular network, a dramatic increase of focal adhesion and an increased expression of "brain specific" cytoskeletal components such as NF-160 and NF-200 neurofilament proteins. C-3-G treatment also induced increase of cAMP levels and up-regulation of tyrosinase expression and activity resulting in an enhanced melanin synthesis and melanosome maturation. Up-regulation of the melanoma differentiation antigen Melan-A/MART-1 in treated cells respect to the untreated control was also recorded. Data obtained provide evidence that a single treatment with C-3-G is able to revert the human melanoma cells from the proliferating to the differentiated state. We conclude that C-3-G is a very promising molecule to include in the strategies for treatment of melanoma; also because of its nutritional relevance.

Thymosin alpha 1 activates dendritic cells for antifungal Th1 resistance through toll-like receptor signaling

Dendritic cells (DCs) show a remarkable functional plasticity in the recognition of Aspergillus fumigatus and orchestrate the antifungal immune resistance in the lungs. Here, we show that thymosin alpha 1, a naturally occurring thymic peptide, induces functional maturation and interleukin-12 production by fungus-pulsed DCs through the p38 mitogen-activated protein kinase/nuclear factor (NF)-kappaB-dependent pathway. This occurs by signaling through the myeloid differentiation factor 88-dependent pathway, involving distinct Toll-like receptors. In vivo, the synthetic peptide activates T-helper (Th) cell 1-dependent antifungal immunity, accelerates myeloid cell recovery, and protects highly susceptible mice that received hematopoietic transplants from aspergillosis. By revealing the unexpected activity of an old molecule, our finding provides the rationale for its therapeutic utility and qualify the synthetic peptide as a candidate adjuvant promoting the coordinated activation of the innate and adaptive Th immunity to the fungus.

Vaccination with a synthetic nonapeptide expressed in human tumors prevents colorectal cancer liver metastases in syngeneic rats

In previous studies, the antigen CSH-275 (RTNKEASIC) was found expressed in tissue specimens from colorectal cancer but not in normal colonic mucosa. It was also naturally expressed in the DHD-K12 experimental colorectal cancer in BDIX rats. In this study, we describe the effect of vaccination with the synthetic nonapeptide CSH-275 in preventing tumor growth in a model closely mimicking the clinical situation of liver metastases, after surgical resection of primary colorectal cancer. A vaccination protocol using CSH-275, conjugated with complete or incomplete Freund's adjuvant, was carried out to determine the effect in preventing the progression of liver metastases induced by DHD-K12 cells injected in the splenic vein (preventive vaccine). An additional vaccination procedure was carried out to determine the effect on s.c. tumor growth (therapeutic vaccine). A significant improvement in survival along with the prevention of liver metastases formation and reduced growth of s.c. tumor were observed. CSH-275 vaccination resulted in a significant increase in CTL activity against autologous DHD-K12 cells in DHD-K12 tumor-bearing rats and the generation of a CTL response against DHD-K12 cells in DHD-K12 naive rats. Vaccination also induced massive infiltration of CD8(+) cells in tumor. These results demonstrate that CSH-275 is a new molecular target for colorectal cancer immunotherapy; it is also an excellent candidate for preclinical studies because it is naturally expressed on tumors in a fully competent syngeneic animal, which reproduces the clinical pattern of cancer progression.

Thymosin alpha(1) in combination with cytokines and chemotherapy for the treatment of cancer

Multiple therapeutic approaches have been tested in different experimental tumour models and in human cancers. Most part of them are based on the hypothesis that the inhibition of tumour growth requires a strong immune response in which a main role is played by CTLs. It is known, however, that an efficient CTL response requires expression of tumour antigens, MHC class I surface molecules presentation, expression of different co-stimulatory molecules and a sustained generation and proliferation of specific cytotoxic CD8+ cells with an efficient CD4+ cooperation. In this context, our group has extensively explored a protocol of combined therapy consisting of the use of chemotherapeutic agents associated with thymosin alpha 1 (Talpha 1) and different cytokines, whose efficacy has been demonstrated in experimental models as well as in human cancers. In this manuscript, the main data supporting a pivotal role of Talpha 1 in such combination protocols are reviewed. In particular, a special mention of the molecular mechanisms underlying the effects of Talpha 1 on immune effector cells as well as on target tumour cells is provided. These data contribute to explain the mechanism of action of Talpha 1, when used in combination therapy, for the treatment of cancer and provide new insights in predicting further possible applications of this peptide in other pathological conditions.

Combination therapy in the treatment of chronic viral hepatitis and prevention of hepatocellular carcinoma

Treatment of chronic hepatitis B and C viruses (HBV and HCV) is still disappointing, and both are the major causes of liver cirrhosis and hepatocarcinoma. Interferon and lamivudine are the registered drugs for chronic HBV but are scarcely effective on HBeAg-negative patients, and resistance due to virus mutation is the rule with lamivudine. Interferon and ribavirine represent the standard treatment for chronic HCV but less than the half of the infected population is eligible for this treatment and less of the half of treated patients will experience a sustained response. No single new drug to date has shown the potential to overcome this dismal picture. Combined strategies are thus the currently most available approach to improve the response rate of chronic HBV and HCV infection, with a subsequent decrease in the number of patients developing hepatocellular carcinoma (HCC). Combination of thymosin alpha 1 with interferon or antiviral agents is currently the most promising option, but nontoxic immunomodulants, such as oral MIMP, should be explored. This review focuses on the difficulties with current therapy and the rationale for use of combination therapy with thymosin alpha 1 for both HBV and HCV therapies.

Nerve growth factor: neurotrophin or cytokine?

Nerve growth factor (NGF) is a neutrophin exerting an important role in the development and functions of the central and peripheral nervous system. However, it has recently been documented that several immune cells - such as mast cells, lymphocytes and eosinophils - produce, store and release NGF. Moreover, NGF high and low affinity receptors are widely expressed in the immune system, thus indicating the potential of responding to this neurotrophin through an autocrine mechanism. In fact, NGF influences development differentiation, chemotaxis and mediator release of inflammatory cells as well as fibroblast activation through a complex network influenced by other pro-inflammatory cytokines. Finally, NGF is increased in biological fluids of several allergic, immune and inflammatory diseases. Data reviewed suggest, therefore, that NGF might also be viewed as a (Th2?) cytokine with a modulatory role in allergic inflammation and tissue remodeling.

Montelukast, a leukotriene receptor antagonist, in vernal keratoconjunctivitis associated with asthma

OBJECTIVE

To evaluate the effects on signs and symptoms of a coexisting vernal keratoconjunctivitis in patients treated with oral montelukast sodium for asthma.

METHODS

Twelve patients with vernal keratoconjunctivitis and asthma were enrolled in this pilot study. Topical eyedrops or any systemic treatment was discontinued for at least 7 days before montelukast treatment. Patients were asked to grade their ocular discomfort daily. The following signs and symptoms were also recorded and graded through medical examination at baseline,after 15 days of treatment, and 15 days after treatment discontinuation: physician-evaluated tarsal and bulbar papillae, hyperemia, secretion, and chemosis; and patient-evaluated itching, burning, tearing, photophobia, foreign body sensation, secretion, and redness. Peak expiratory flow rate at 8 AM was also recorded. Samples were collected at the same time points for enzyme-linked immunosorbent assay measurement of leukotriene B4 in tears and leukotriene E4 in urine.

RESULTS

Eight of the 10 patients evaluated reported a reduction in symptoms at the end of treatment. Montelukast treatment significantly decreased physician-rated hyperemia, secretion, and chemosis as well as patient-rated burning, tearing, photophobia, secretion, and redness. Effects persisted 15 days after discontinuation of treatment. Clinical changes were associated with a significant increase in leukotriene B4 in tears and a significant decrease in leukotriene E4 in urine after 15 days of treatment.

CONCLUSION

The significant and persistent reduction of ocular signs and symptoms in asthmatic patients with vernal keratoconjunctivitis treated for 15 days with montelukast strongly suggests the need for double-masked placebo-controlled trials to confirm the potential of this new treatment in vernal keratoconjunctivitis.

Nerve growth factor and asthma

An increasing body of evidence shows that nerve growth factor (NGF) exerts biological activity not only on the central and peripheral nervous system, but also on the immune system thereby influencing allergic diseases and asthma. (1) NGF circulating levels are increased in patients with allergic diseases and asthma, and are related to the severity of the inflammatory process and disease. In vernal keratoconjunctivitis, NGF plasma levels correlate with the number of mast cells infiltrating the conjunctiva, and NGF mRNA is increased in nasal mucosal scrapings of patients with allergic rhinitis who have high levels of NGF in serum and nasal fluids; NGF is further increased in nasal fluids after specific allergen challenge. (2) NGF is produced and released by several modulatory and effector cells of allergic inflammation and asthma, for example T-helper 2 lymphocytes, mast cells and eosinophils. (3) NGF receptors are expressed on the conjunctival epithelium of patients with allergic conjunctivitis and the number of NGF-receptor positive cells is increased in the conjunctiva of these patients. Indeed, local administration of NGF induces fibroblast activation and healing processes of human corneal ulcers, which suggests that NGF plays a role in tissue remodelling processes occurring in asthma. (4) NGF increases airway hyperreactivity to histamine in an animal model of asthma, while anti-NGF treatment reduces airway hyperreactivity induced by ovalbumin topical challenge in the sensitized mouse.